Calling Matlab MEX Files in LabView ?

What is the procedure to call a MATLAB MEX File in Labview?

Nope Battler.
I didnt find any help regarding Matlab MEX DLLs on that link by Chris.
I presume if they are keeping mum, there is no solution possibly.
Btw, I migrated my testing from LV to MSVC.
Its a lot more easier to call Matlab MEX DLLs from MSVC.
http://www.mathworks.com/support/tech-notes/1600/1605.html

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I would like to run Matlab mex file in Labview - how to do this?

Hello
In order to run Labview without Matlab beeing installed I have to compile the matlab files, right? So I also want to run those files in Labiew, and I do not know how. Anybody can help.
Thanks a lot
kind regards
Pawel

Pawel,
You can create a DLL in Matlab. To compile this DLL you should use both LabVIEW and Matlab typedefs. The Math Works offers a C library with functions for accessing Matlab files. You can use this library to create a DLL. Then import the DLL into LabVIEW by using Call Library Function VI located under Functions>>Advanced palette.
To call Matlab scripts from within LabVIEW, you have to have Matlab installed on the machine. The Script Node (Matlab script) function is located in Functions>>Mathematics>>Formula palette.
Here are some useful links:
- description of those C functions
[http://www.mathworks.com/access/ helpdesk/help/techdoc/apiref/apiref. shtml]
- how to download and compile (it will be a little bit different if you want to use CIN)
[htt
p://www.mathworks.com/support/ solutions/data/8757.shtml]
- MAT-file format if you want to develop your own LabVIEW utility to do the job
[http://www.mathworks.com/access/ helpdesk/help/pdf_doc/matlab/ matfile_format.pdf]
Hope these suggestions pointed you in the right direction.
Zvezdana S.
National Instruments

Segmentation fault when calling gpctr function from matlab mex file

I am trying to write a simple mex file for square wave generation using counter1 of PCI-6035E. I am using matlab's native compiler to compile and link with the nidaq32 library, ver.6.9.3, with no errors. When the mex function is called from a matlab script, however, the program crashes at the first call, to reset the counter. (I can generate a square wave with the test panel.)

Sorry for the delay in responding. I got caught up in other stuff. I am attaching my little program as requested. As you can see, I have just wrapped a mexFunction call round the example code for square wave generation. After I posted this, I tracked down a copy of BorlandC++, installed it on my computer and recompiled using that compiler and *b.* libraries. And would you know it, the program works. The question remains, though, why it doesn't work with Matlab's native lcc compiler. Plus, I have limited disk space, so if I can do without BorlandC, I can use the extra room. The runtime error was a Segmentation fault that I traced to the first call to GPCTR_Control.
Attachments:
pulsegen.c ‏4 KB

Calling Matlab 7.1 from LabView 6.1

Hello,
I am using LabView 6.1 and I have recently installed Matlab 7.1 on the same machine.
When I try to call Matlab by a Matlab script node, I only get the error
message that the script could not be executed and that a failure
occured calling the script server. (This does not depend on what script
I implement.)
Earlier, I had Matlab 6.5 which worked well with the script nodes.
What can I do to get the script nodes running?

Hello ffffff
I can pretty much assure you that LabVIEW 6.1 has not been tested with MATLAB 7.1, and "officially" I might go so far as to say it's not supported.
That said, you might try downloading the MATLAB Script.zip file attached to this KnowledgeBase entry:
http://digital.ni.com/public.nsf/allkb/4475BC3CEB062C9586256D750058F14B
Follow the directions in the KB to update the matscript.dll file in your LabVIEW 6.1 distribution, and this might resolve the issue. This addressed numerous issues with the MATLAB script node so that version 7.0 of MATLAB would work well with LabVIEW. I'm not sure if this version of the matscript.dll has been tested with LabVIEW 6.1 or not, but in theory it should work. Also, if the problems you are encountering are new to MATLAB 7.1 in specific, there may not yet be a solution for this; I don't know how new MATLAB 7.1 is.
Good luck!
Message Edited by Jeff B on 02-16-2006 07:44 AM

Calling matlab 6.0 from labview

I need know how to start Matlab 6.0 from Labview, and I will need to pass strings of script commands (for example, a=10;b=5;c=b/a;disp(c)) to Matlab to be executed. And Labview will need to get the result (value of c) back. Thanks for all the help!

You can use the matlab script funtion under Functions»Mathematics»Formula»MATLAB Script
Also you can find the matlab script examples in the examples»communication»Importing MATLAB Script.
I hope this helps... Have fun
Ogulcan

How can i call a DLL file from labview?

Iam using a sensoray 2601 module.It is given as DLL file(S2600.DLL).How can i call this function from LabVIEW?
Please Mark the solution as accepted if your problem is solved and donate kudoes

As far as I can tell problems might occur with the call library function node if the the DLL from visual basic is actually an ActiveX dll if that is the case it seems calling the dll by using the Invoke node is the way to go.
Have a look at this
/sletten

I want to read a Matlab MAT file into labview.

I do not have Matlab. I have a series of *.mat files that are created by another program that I want to read into LabVIEW. The *.mat files should contain a very long 2 dimensional array of complex numbers, with only 2 columns. I am hoping that the *.mat format is straight forward. I need to read this into a LabVIEW array to manipulate it.
Has this been done? I've found several routines that allow you to save data from LabVIEW into a *.mat file so that Matlab can read it, but I have not seen anything that goes in my direction. Any help is appreciated.
Mike

Oh, yeah, that certainly makes a big difference.
You're even luckier that I was still bored, so I whipped something together.
See attached.
Couple of things:
(1) I couldn't test it for all data types so the "Parse Data" VI may need to be tweaked for some of the data types.
(2) Your file contained multiple variables and the one matrix of complex values was a 1D array so you may need to insert a "Transpose 2D Array" function where the bundle function is for your 2D array.
(3) A couple of the variables were character arrays but Matlab stores the individual characters as floating point numbers between 0 and 255 representing ASCII-encoded characters. These are the "XUnit" and "YUnit" arrays.
For your reference, the MAT file format is at http://www.mathworks.com/access/helpdesk/help/pdf_doc/matlab/matfile_format.pdf
Oh, I think I may have left breakpoints in when I saved the VI. Sorry about that. You should remove them when you run the VI so they don't become annoying.
Message Edited by smercurio_fc on 02-09-2006 05:07 PM
Attachments:
Read Level 4 MAT File.zip ‏69 KB

Is it possible to read data from MATLAB *.mat file using LabVIEW?

I have *.mat file from Matlab with some data. Does anybody know how to extract them from this file. I need to know the file format.
Oleg Chutko.

The Mathworks site is pretty good about having documentation for the formats of their file types. I recommend looking there for the format.

Error 1050, when calling MATLAB 7.1 from LV8.0 - Function Definitions not allowed.

I am trying to call a MATLAB M-file from LabVIEW 8.0. I keep getting Error Code 1050:
"Error 1050 occurred at LabVIEW: Error occurred while executing script. Error message from server: ??? Error: Function definitions are not permitted at the prompt or in scripts.
. in rickfito.vi->impedo.vi
Possible reason(s):
LabVIEW: Error occurred while executing script"
I tried running the sample MATLAB script example on the knowledge base, and everything works fine.
I am guessing that this error is happening because I have functions defined in the MATLAB script. But i thought this is better programming techinque. Also, the MATLAB window opens up when I start the VI.
Is there a way around this? I really do not want to remove the function definitions on the script.
Thx,
Pelo...

First, see if the Matlab Script Node is trying to open any files. If
so, then make sure that the current Matlab directory is set to the
directory where that file is located. The Matlab script node in LabVIEW
does call the Matlab script server and executes the function in the
Matlab script node through Matlab. Therefore, even though LabVIEW may
be in the correct directory where the file is located, make sure Matlab
is as well.
The error may also occur if there is a disruption
in the script server between MATLAB and LabVIEW and the connection was
never re-established (possibly by closing MATLAB prematurely). Close
both LabVIEW and MATLAB then relaunch them both and run the VI.
MATLAB®
is a registered trademark of The MathWorks, Inc. Other product and
company names listed are trademarks and trade names of their respective
companies.
-Bob
-Bob

How to open a .MAT file in LABVIEW

Hey everyone,
I currently have a .MAT image file which I would like to open in LABVIEW to apply some image filters. However, I am unsure as to how to open the .MAT file in LABVIEW. Ideally I would like to be able to open the .MAT file without using matlab, and it seems the only way to accomplish this task is through the mathscript node. I have attached an example of the image im trying to open, as well as the LABVIEW program which I would like to use on the image. Thanks for the feedback! =]
Attachments:
MAT_Image_Adjust.zip ‏1779 KB

Hi Boiler,
1) Do you have a choice in the format you export your data from MATLAB?
"ASCII Format
Complete the following steps if you want to import or export data between LabVIEW and the MATLAB® environment, the process is straightforward as long as you are using ASCII format.
From the MATLAB® environment to LabVIEW
To save a vector or a matrix Xin ASCII format with tab delimiter, enter the following in the command window or m-script file in the MATLAB® environment:
>>SAVE filename X -ascii -double -tabs
This creates a file whose name is filename, and it contains the data X in ASCII format with a tab delimiter.
Import the file into LabVIEW using the Read From Spreadsheet File VI located on the Programming»File I/O palette.
2) Have you tried using the mathscript node? Did you get any errors?
"Binary Format
Complete the following steps if you want to import or export data between LabVIEW and MATLAB®.
From the MATLAB® environment to LabVIEW
To read a .mat file in LabVIEW would require a VI to parse the file. This may be easier if each variable is saved to a separate file.
" -- this was done here, no ideas if it still works,
I want to read a Matlab MAT file into labview
Hope this helps, James
Kind Regards
James Hillman
Applications Engineer 2008 to 2009 National Instruments UK & Ireland
Loughborough University UK - 2006 to 2011
Remember Kudos those who help!

Running exe files in labview (or alternatives)

I am currently trying to make LabVIEW communicate with a DT3155 frame grabber. It reads exe files programmed in c. I initially wanted to call the dll libraries of the frame grabber and rewrite the code into sub-VI's, but then realized it would be much too big for me to make. Is there any way to call on exe files in LabVIEW, so that I can run a program whenever I wanted to perform a function? And if not, what other options can I consider utilizing? Sorry if this question is too basic, I'm just starting to learn LabVIEW. Thanks in advance for any help you guys can offer to me. ~Josh

To run an EXE, you can use the System Exec function on the communications palette. You can pass command line parameters to the EXE. The tricky part is usually getting the EXE to pass data back to LabVIEW. I did a Google search for DT3155 and LabVIEW and found a couple places that sell LabVIEW drivers. This is the option that I would go with. One of them is at http://www.alliancevision.com/net/lv_driv_frmgb.htm.

Matlab workspace not getting updated while labview mex file is running

Hi,
Let me start from the overview of the system for better understanding.
The system is to acquire data from a DAQ6070e using labview 7.1 . this data is then to be used in matlab for processing. All this needs to happen in real time hence the data is to be acquired from labview and outputted into matlab in real time.
in order to do this we generated the labview and the matlab codes seperately. After days of hard work we managed to import the labview vi into matlab using a math interface toolkit, but now have run into another interesting problem.
the workspace in matlab is not getting updated during the time the labview vi is running inside matlab. it only updates after the vi has run . for example if i need to monitor the system for 300 seconds then ideally the labview vi should output the samples for each acquisition and output it to matlab, what actually is happening is that the labview keeps running for 300 seconds without outputting any data during those 300 seconds and only outputs the last set of acquisition values at the end of the 300 seconds. Which beats the purpose of the whole program.
Kindly help
Regards
Manuj

Thanks Mate,
What you said about "MEX file will not be able to "store" data between runs" ,i realised in the morning. as a result i dont think your suggestion of for loop will also be effective as labview mex file will not acquire data during matalb code execution and vice versa.
Hence i have decided to do it the other way...we will now try to run the matlab code in labview.
this leads to other problem
As this is a real time operation i need to find out a way of storing the data into computer memory and then reading from it(when i say memory i do not mean writing it to a file and readin from it as that is slow) becasue i think the buffer i am specifying in my AI config is not big enough.
I was thinking maybe i should use a RT FIFO queue but then i have not been able to find out the difference between buffer memory and fifo memory. ie is buffer memory supposed to be the ram memory or is it the hard disk memory?
I am posting the vi here for easy understanding
All help is very much appreciated
Attachments:
RT-loop2ver21.vi ‏231 KB

Error in Calling a dll built in labview from Matlab standalone

hello,
The problem I encountered is in the use of the math interface toolkit. I
created a dll which performs data fitting using a labview vi which i converted into a dll using the
math interface toolkit.
This dll is then called from a standalone matlab program. It works fine in the computer where I
create the matlab standalone program and labview dll. Howerver when i export to another
computer the matlab part runs fine but an error is reported when it tries to
call the labview created dll.
"One or more output arguments not assigned during call Parfit.dll"
The files related to this problem in the math interface toolkit (the labview vi, the corresponding dll and the matlab .m and .fig files and the standalone exe are in the attachment and named MathITproblem.zip
The matlab run time engine(for matlab 7) and labview runtime engine(ver 7.1) must be installed for this matlab file to run. the run time engines are downloadable from the web.
Does any one know the source of this error or encountered it before?
thanks
Attachments:
MathITproblem.zip ‏1263 KB

Hi Srinivas,
Just another note, I noticed that the Math Interface Toolkit version (MIT) 1.0 is not compatible with LabVIEW 7.1. You’ll need version 1.0.1. of the MIT toolkit in order for it to work with LabVIEW 7.1.
The LabVIEW 7.0 lvanlys.dll is also attached. I had to rename it with a .txt extension, so you’ll want to delete the extension.
Kileen
Attachments:
lvanlys.dll.txt ‏516 KB

How to output data when converting labview vi into matlab mex functions

Hi,
I am a fairly new user to labview and am currently working on labview
7.1. I have created a labview vi which can extract data from ni daq
6070e in real time. The problem is that this code has to be converted
so that it can be used with matlab.in order to do that i am using math
interactive tool kit which converts the labview code into mex files
which can then be used in matlab. Unfortunately i have not been able to
figure out how to output this data so that it can be processed in
matlab easily. i cannot afford any loss of information and all the
output must happen in real time. the o/p must take place after the fft
has been done. i am attaching the vi for convenience.There are 10
broken wires ,and this is the place where i want the o/p to be
generated.
Also do let me know if this vi can be further improved.
Regards
Attachments:
RT_loop2ver4_working.zip ‏642 KB

Manuj,
You seem to have misunderstood the way in which LabVIEW processes data. The code that you have produced will run in exactly the same way without the need for the case structure.
The code does not actually run the data from the previous case. It is merely processing data from the previous loop iteration, regardless of the case. If you were to remove the case structure, leaving only one copy of the code intact, and remove the toggle switch you have produced, or used the shift register which, I assure you would have worked, then you will have exactly the same functionality.
I have attached an example that uses the shift register to toggle cases, but also iterates that the case structure is not needed by using the same feedback node (and code) without a toggle switch or case structure.
Hope this helps you optimize your code
Regards
AdamB
Applications Engineer
National Instruments UK
Applications Engineering Team Leader | National Instruments | UK & Ireland
Attachments:
CASE_NO-CASE_Example.vi ‏24 KB

Dynamically call Matlab file

A colleague of mine has made a Matlab .m file that I should call in from LabVIEW. I have imported the function into a Matlab script node. I haven installed Matlab on my PC and therefore i get a licence error. Before I ask my boss for a matlab licence i will ask this forum if there is another way. The Matlab function is still under development and will change a number of times. I could be nice if I didn't have to import the function every time the .m file changes
1. Could I use a MathScript node instead? Or is there another way for importing or calling that function without a Matlab Licence?
2. Is it possible to dynamically call the Matlab Script node/ MathScript node eg via a propertynode or another method instead of importing the function?

I know the Model Interface Toolkit has some options for Matlab but I think that is only for compiled Matlab models.
http://sine.ni.com/nips/cds/view/p/lang/en/nid/211815
Unofficial Forum Rules and Guidelines - Hooovahh - LabVIEW Overlord
If 10 out of 10 experts in any field say something is bad, you should probably take their opinion seriously.

Calling Matlab MEX Files in LabView ?

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